A soilless culture system to grow out-of-season asparagus with a high marketable value.

摘要

In recent years, asparagus production in Belgium, France and, to some extent, in Italy, has decreased mainly because of soil exhaustion and soil-borne diseases. Fresh asparagus imports are increasing in Italy, as is the demand for asparagus for processing. Greenhouse soilless culture can limit pest diseases, optimize, standardize and increase spear production, and reduce labour costs. Furthermore, greenhouse production allows earliness and out-of-season production so growers can obtain a higher market price. Plastic boxes (460x265x245 mm) were lined with Styrodur (isolating sheets), and filled either with local soil or growing media (60% peat and 40% perlite, by volume). Asparagus rhizomes were kept from February to July in a chamber at -1 degrees C, then from August to September at 0 degrees C and finally used for greenhouse production. Either 2 or 3 rhizomes were placed in each box, either at the beginning of October or at the beginning of November. Boxes were placed on a bench in an experimental greenhouse, and irrigated throughout the experiments as needed. Fertilizer application took place either every week or every 2 weeks, using Tipo OT (Valagro), a commercial solution for hydroponics, at 1 g/litre. Harvesting started on 24 November 2000, ending on 26 January 2001 (1st year), then started again on 11 October 2001, ending on 21 December 2001 (2nd year). Results indicate that the forcing period was the most effective treatment for conditioning spear production in both years. The soilless culture system allowed production from the first year of growth, a plus for the asparagus crop.